An internal dye diffusion transfer print is a one-of-a-kind, "instant" color photograph most commonly marketed by the Polaroid Corporation. The process uses a multi-layered film pack that includes an image-receiving layer, a reagent-collecting layer, and layers sensitized to the primary additive colors alternating with layers of primary subtractive color dyes. The film pack is ejected from the camera immediately after exposure, breaking open a pod of reagent that starts the development process. The exposed silver in the additive color layers blocks the diffusion of the complementary subtractive colors upward to the image-receiving layer, while the reagent-collecting layer turns opaque, masking the residual silver and dyes that did not diffuse to the image-receiving layer. Dye diffusion prints are favored for the instant results they provide and for particular image manipulation techniques that are possible during the development process.